shrewd in WordNet English dictionary

1. marked by practical hardheaded intelligence
   "a smart businessman"; "an astute tenant always reads the small print in a lease"; "he was too shrewd to go along with them on a road that could lead only to their overthrow"
   astute  sharp  shrewd 
   
2. used of persons
   "the most calculating and selfish men in the community"
   calculating  calculative  conniving  scheming  shrewd